1. Field of the Invention
The invention relates to a transceiver module for the high frequency domain including at least a transmission path having an HF power amplifier, a receive path having a low-noise receiving amplifier, and a transmit/receive switch which permits switching from the transmit path to the receive path.
2. Description of the Related Art
In many high frequency applications, for example in the radar art, it is necessary to selectively couple a transmission path, which generally includes one or a plurality of high frequency (HF) power amplifiers, or a highly sensitive receiving path to a common transmit/receive path, for example a radar antenna. For this purpose a transmit/receive switch is employed which is also called a T/R switch or duplexer.
The radar art frequently employs a circulator for this purpose. Such a circulator has the drawback that it is mechanically sensitive, particularly to high accelerations, for example impact or shock, and additionally has an often insufficient, small operating temperature range. A circulator has a relatively large volume so that an often required small and lightweight structure, for example within the framework of an integrated structure, is not possible. If, for example, a radar system is intended to transmit and/or receive circularly polarized radiation, two circulators are required, which is a drawback, and they must additionally be arranged as far apart from one another as possible in order to prevent bothering magnetic couplings between them. Moreover, a circulator is an expensive component so that its use leads to disadvantageously high costs, particularly in phased array antennas.
As an alternative, it is possible to employ a so-called SPDT (single pole double throw) switch. A drawback with an SPDT switch is that it can be used only for small transmitting powers, that is, up to about 1 W, and moreover does not provide protection for the transmission path against unduly high reflected HF powers received, for example, by a radiator element.